Flowing gas streams often contain particulate material that must be removed from the gas stream. The particulate material may be an undesirable contaminant in the gas stream. Alternatively, the gas stream may contain a desirable particulate material, for example, in a process for manufacturing the particulate. Similarly, flowing gas streams may contain liquids or aerosols, either desirable or undesirable, that must be removed from the gas stream.
There presently exist several systems and methods for removing particulate material and/or liquids from gas streams, including inertial, viscous, diffusion, filtration, and electrostatic separation systems and methods. These existing systems for separating solids and liquids from gas streams may be inefficient, pose unnecessary environmental hazards, and may be costly to manufacture and operate.
By way of example, a natural gas transmission company was recently experiencing a problem with its conventional filter separators at a compressor station in Louisiana. Approximately every six weeks, the compressor station was experiencing harmful slugs of lubrication oil mixed with a black powder. This mixture would coat the filters in the filter separators and compromise the elements, thus allowing the contaminated gas to flow through the separator and into the downstream compressor equipment. As a result, the compressors had to be shut down for approximately three days while personnel worked around the clock to manually change and dispose of the contaminated and potentially hazardous filter elements. Further background regarding available systems and methods may be found in the applicant's U.S. Pat. No. 7,875,103, which is hereby incorporated by reference.
U.S. Pat. No. 7,875,103 discloses a viscous impingement particle collection and hydraulic removal system. The system solves many of the problems associated with the prior art by providing a plurality of helical separators positioned in a gas flow path and connected through a sump to a duplex-filtered side stream. Each helical element is typically about 4 inches in diameter and 5 inches in height, and forms helical channels that turn a total about 180 degrees. The channels are formed by parallel fins spaced apart about 0.5625 inch, with an inner radius of about 0.28125 inch and short chamfers on the exterior edge of each fin. With typical gas flow rates, this configuration generates centripetal acceleration forces of about 1,300 G's.
Helical elements such as those disclosed in U.S. Pat. No. 7,875,103 are typically machined from a solid rod of a high grade 4130 chrome molybdenum, 304/316 stainless steel, ceramics, or other suitable material depending on the particular flow application. The complex geometry of the helical channels, inner radius, and fins may also require extensive machining and lengthy processing on a large, five-axis CNC milling machine. Thus, manufacturing each of the 100 or more helical elements often needed for a single separator may prove costly and time consuming.
Accordingly, there exists a need for new systems and methods for removing particulate and liquids from flowing gas streams wherein the new systems and methods are capable of effective operation at varying gas flow rates and potentially high liquid-to-gas weight ratios. Preferably, such systems should also be simpler and less expensive to manufacture.